Electric shock hazards in cardiac catheterization

• It has long been recognized that the heart may be fibrillated as well as defibrillated by electric shock. Burchell1 recently emphasized the potential hazard of ventricular fibrillation from electric shock if a pacemaker and an electrocardiograph were connected so that a current existed between them. It seemed pos-sible that many of the techniques used in a cardiac catheter laboratory, especially those involving electrode catheters, may pose a similar threat to patients. The present study was designed to deter-mine the minimum current and voltage that, when delivered directly to the heart via intra-cardiac catheters, would cause fibrillation in dogs. It was found that a very small current or voltage could produce ventricular fibril-lation. Therefore, a detailed analysis of the equipment in a routine catheter laboratory was undertaken to determine usually unrec-ognized sources of such currents. As a result of these analyses, recommendations are made indicating how this potential hazard can be minimized